export default {
  bind(el: HTMLElement) {
    // 弹窗的容器
    let dialogHeaderEl = el.querySelector('.el-dialog__header') as HTMLElement
    const dragDom: any = el
    dialogHeaderEl.style.cssText += ';cursor:move;'
    const getStyle = (function () {
      if (window.document.currentStyle) {
        return (dom: any, attr: any) => dom.currentStyle[attr]
      } else {
        return (dom: any, attr: any) => getComputedStyle(dom, null)[attr]
      }
    })()

    dialogHeaderEl.onmousedown = (e) => {
      // 鼠标按下，计算当前元素距离可视区的距离
      const disX = e.clientX - dialogHeaderEl.offsetLeft
      const disY = e.clientY - dialogHeaderEl.offsetTop

      const dragDomWidth = dragDom.offsetWidth
      const dragDomHeight = dragDom.offsetHeight

      const screenWidth = document.body.clientWidth
      const screenHeight = document.body.clientHeight

      const minDragDomLeft = dragDom.offsetLeft
      const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth

      const minDragDomTop = dragDom.offsetTop
      const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomHeight

      // 获取到的值带px 正则匹配替换
      let styL = getStyle(dragDom, 'left')
      let styT = getStyle(dragDom, 'top')

      if (styL.includes('%')) {
        styL = +document.body.clientWidth * (+styL.replace(/\%/g, '') / 100)
        styT = +document.body.clientHeight * (+styT.replace(/\%/g, '') / 100)
      } else {
        styL = +styL.replace(/\px/g, '')
        styT = +styT.replace(/\px/g, '')
      }

      document.onmousemove = function (e) {
        // 通过事件委托，计算移动的距离
        let left = e.clientX - disX
        let top = e.clientY - disY

        // 边界处理
        if (-left > minDragDomLeft) {
          left = -minDragDomLeft
        } else if (left > maxDragDomLeft) {
          left = maxDragDomLeft
        }

        if (-top > minDragDomTop) {
          top = -minDragDomTop
        } else if (top > maxDragDomTop) {
          top = maxDragDomTop
        }

        // 移动当前元素
        const cText = `;left:${left + styL}px;top:${top + styT}px;`
        dragDom.style.cssText += cText
        dragDom.setAttribute('data-pos', cText)
        // emit onDrag event
        // vnode.child.$emit('dragDialog');
      }

      document.onmouseup = function (e) {
        document.onmousemove = null
        document.onmouseup = null
      }
    }
  },
  update(el: HTMLElement, binding: any) {
    if (!binding.value) {
      const pos = el.getAttribute('data-pos')
      if (pos) el.style.cssText += pos
    } else {
      el.style.cssText += `;left:0px;top:0px;`
    }
  }
}
